Whoever holds this book leaves a ghostly shadow of their hand on its grey cover. Made of heat-sensitive material, the cover temporarily records the imprint of the reader’s hand. It is a striking visualization of Sentient City’s subject, for as sensors and data processing capability are increasingly embedded in the physical fabric of urban environments, so we now leave a data trail as we move through the city, a digital shadow stretching across the urban topography.

New digital technologies, from electronic identification tags to CCTV cameras linked to car number plate and even face recognition software, are logging the life of the twenty-first-century city. A truly “sentient” city may still be science fiction, but buildings and streets are being equipped with the ability to sense, process and record information about our behaviour. New Songdo, in South Korea, is the prototype of this “smart city” of the future. Due to open in 2015, it will be the first city to boast an electronic central nervous system: a network of sensors and microprocessors spread throughout the urban fabric and jacked into city-wide computer systems. In the future, everything will be connected.

According to Mark Shepard, the “data clouds” of the twenty-first century are now more important than the “formal organization of space and material in shaping our experience of the city”. Smart phones, locative media and augmented reality apps are transforming how we see and interact with the city: “The city becomes a network of nodes and pathways through which we circulate like data packets.” Inspired by Archigram’s seminal 1963 exhibition “Living City”, he argues that these new technologies not only demand “a reconsideration of the role of architects and the profession of architecture”, but also a radical rethink of cities and indeed citizens.

This book has grown out of a 2009 exhibition, “Toward the Sentient City”, commissioned by the Architectural League of New York, for which five teams of architects, artists and technologists were asked to imagine the impact of ubiquitous computing on cities and urban life. They range from worthy exercises in raising public awareness about waste disposal by attaching smart tags to rubbish (“Trash Track”) and an attempt to transform the public spaces of an entire city into a vast open-plan office (“Breakout!”), to the wonderfully subversive “Too Smart City”, in which three pieces of street furniture are rendered utterly useless by advanced technology: a “Too Smart Trashcan” that violently ejects unwanted rubbish after it has been discarded; an electronic sign that turns to face passersby and bombards them with rules and regulations; and a bench that only permits a person to remain seated for a limited time before dumping the suspected vagrant onto the ground.

As “Too Smart City” (designed by David Jimison and Joo Youn Paek) shows, new technology needs to be implemented judiciously. Sentient City contains a dozen essays exploring the impact of the new technologies, including a piece by Saskia Sassen who finds that underlying today’s fragmented topographies, new “invisible circuits” are being created by information and communication technologies, making possible “a new type of cross-border political activism” that is both local and global.

But several contributors raise concerns about this brave new wired world. Martijn de Waal observes that the implicit promise of social and locative media is “that urbanites never have to leave the comfort of being surrounded by like minded people”. This undermines the whole idea of the city as a community of strangers that gains its uniquely creative dynamism from the need to negotiate difference, principally in public spaces. Trebor Scholz rightly raises concerns about the monetization of information. The “global data field” we generate will be mined by governments and big business, he says: “in the Sweatshop City our data body never sleeps”.

In this fast-moving field, reality is rapidly overtaking imagination and while some of the case studies in Shepard’s book already seem dated, the essays represent a timely attempt to stimulate debate about the shape of tomorrow’s sentient city.

[N.B. This version may differ slightly from the one printed in Icon magazine. Image by David Jimison and Joo Youn Paek]

Today, for the first time in history more than half the population of the planet live in cities. Two hundred years ago, just three per cent were city dwellers, but by 2050, 75 per cent will be urbanites. City is the ultimate guidebook for our urban age, taking the reader on a journey through the past, present and future of the world's cities. Illustrated throughout and with essays on everything from Ellis Island and Eco-cities, to Street Food and Tahrir Square, this is a fascinating celebration of our greatest creation – the city. More